To meet the demand for wireless data traffic, which has increased since deployment of 4th-generation (4G) communication systems, efforts have been made to develop an improved 5th-generation (5G) or pre-5G communication system. Therefore, the 5G or pre-5G communication system is also called a ‘beyond 4G network’ or a ‘post long-term evolution (LTE) system’.
It is considered that the 5G communication system will be implemented in millimeter wave (mmWave) bands, e.g., 60 GHz bands, so as to accomplish higher data rates. To reduce propagation loss of radio waves and increase a transmission distance, a beam forming technique, a massive multiple-input multiple-output (MIMO) technique, a full dimensional MIMO (FD-MIMO) technique, an array antenna technique, an analog beam forming technique, and a large scale antenna technique are discussed in 5G communication systems.
In addition, in 5G communication systems, development for system network improvement is under way based on advanced small cells, cloud radio access networks (RANs), ultra-dense networks, a device-to-device (D2D) communication, a wireless backhaul, a moving network, a cooperative communication, coordinated multi-points (CoMP), reception-end interference cancellation, and the like.
In the 5G system, a hybrid frequency shift keying (FSK) and quadrature amplitude modulation (QAM) modulation (FQAM) and a sliding window superposition coding (SWSC) as an advanced coding modulation (ACM) scheme, and a filter bank multi carrier (FBMC) scheme, a non-orthogonal multiple Access (NOMA) scheme, and a sparse code multiple access (SCMA) scheme as an advanced access technology have been developed.
A communication network in a general 5G system is generated in a form that a coverage of a master evolved node B (MeNB) of which a coverage is equal to or larger than a threshold coverage overlaps with a coverage of a secondary evolved node B (SeNB) of which a coverage is smaller than the threshold coverage. Here, the term MeNB may be interchangeable with the term anchor evolved node B (eNB), and the term SeNB may be interchangeable with the term small eNB, assisting eNB, and slave eNB.
At this time, dual connectivity that one terminal is connected to two or more than two eNBs in a communication system may be implemented in order to a terminal to perform a communication through at least two of eNBs configuring at least one serving cell.
The dual connectivity is configured in order that a terminal may use radio resources provided by at least two different network points, e.g., an MeNB and an SeNB at the same time in a radio resource control (RRC) connected (RRC_CONNECTED) mode. At this time, the at least two different network points are connected one another through an X2 interface using an ideal backhaul or a non-ideal backhaul.
A conventional communication system has provided an evolved packet system (EPS) bearer service to a terminal through a radio bearer (RB) of one eNB.
However, one EPS bearer service has been provided to a terminal through an RB which is set to each of an MeNB and an SeNB, not an RB of one eNB, from a 3rd generation partnership project (3GPP) release-12 (Rel-12), and a bearer form operated like this will be referred to as split bearer.
In the split bearer, an S1-U connection from an evolved packet core (EPC) is terminated at an MeNB, and packet data convergence protocol (PDCP) data is delivered through an X2-U interface between the MeNB and an SeNB. For this, the MeNB performs a routing operation of determining to transmit data of one EPS bearer through which one of a transmission path through the MeNB and a transmission path through an SeNB, and the terminal should perform an operation of sequentially reorders data received from the MeNB and data received from the SeNB according to a sequence number (SN).
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.